1. Field of the Invention
The present invention relates to interactive toys. More particularly, the disclosed toy makes use of passive infrared devices and active software to enable the toy to move and react to nearby heat sources (i.e. a human body). The present invention is a further development of the applicant's prior interactive tracking device disclosed in U.S. patent application Ser. No. 07/277,203 in that it utilizes the PIR(passive infrared) sensors the detect and track a heat source. The present invention is now capable of also chasing or moving away from a detected heat source depending on a chosen mode of operation.
2. Description of the Prior Art
Prior art device in the field of moving devices that react to other sensed objects do so in a very limited way. One such prior art device is the security/intrusion detection system disclosed in U.S. Pat. No. 4,772,875 issued to Maddox. This device comprises a mobile body that can travel on wheels. The body has an array of infrared sensors arcuately disposed around the body that can detect heat sources. A rotating turret has a second detector means, in the form of an active infrared or ultrasonic sensor, to verify the intruder's presence and to initialize an alarm sequence. The head or turret must first rotate to the position of the infrared sensor that gave the initial intruder signal and verify the presence of the intruder with the second sensor. This is not a tracking system in that the device can not actually follow the movement of the intruder and react with its own movements. The turret head of Maddox is not capable of small incremental step rotations necessary for tracking. It is only capable of rotating to a specific sensor position. This leads to a very slow reaction time for the Maddox system as a whole due to its inability to execute fine tuned movements.
The field of view of the Maddox device is one in which a plurality of infrared sensors, usually six, continuously receive information in an overlapping 360.degree. field of view. The great number of sensors is necessary due to the fact that the main array cannot move on its own in order to track a target, which is not its intended purpose, it being instead a detection and alarm system.
Numerous infrared sensor systems are known in the field. Some, such as those disclosed in U.S. Pat. Nos. 4,662,854 and 4,828,525 issued to Fang and Okano respectively, disclose active infrared sensors systems. Active infrared sensors emit an infrared signal as well as receive such a signal. A PIR (passive infrared) sensor is capable of only receiving infrared transmissions and radiation. For a tracking device, a PIR receiver would react to only a narrow defined bandwidth of infrared radiation. An active infrared sensor is usually tuned to a bandwidth that will not be confused with other sources of infrared radiation. Many active infrared systems would not want to be confused by human body radiation and so would have a tuned bandwidth that would prevent reaction to human presence. In a device meant to track humans that bandwidth would be about 9.4 micrometers, this being the natural wavelength of heat radiation given off by human beings.